Day gathers, and now my watch begins.
It shall not end until my death.
I shall take no wife, hold no lands, father no children.
I shall wear no crowns and win no glory.
I shall live and die at my post.
I am the claw in the darkness.
I am the watcher on the Rock.
I am the shield that guards the Pride Lands.
I pledge my life and honor to the Lion Guard, for this day and all the days to come.

I see a parallel here. Kion is not betrothed (neither is Kiara you say - but the only males in SP are the enemy's cubs.), no one addressees him as the prince, he is not the heir (despite being not only a male but also far more responsible and smart, but that's another story) and his destiny is to fight the murderous hordes trying to cross the border, while his sister is being overprotected. Day and night at the post.
I want to see Kion snap. He's the one doing all hard work, despite being a cub, getting nothing in return.

Both the Night's Watch and The Lion Guard are an excellent way of disposing of excess children, giving them an important task, so they're not a threat to the real heir...

TLK, TLG © Disney
ASoiAF © GRRM